1. Field of the Invention
The present invention relates to a spectacle lens supply method, and more particularly, to a spectacle lens supply method for a system which includes a terminal installed at a lens order side and at least a computing device installed at a lens processor side and connected to the terminal through a communication line, for supplying spectacle lenses.
2. Description of the Related Art
Conventionally, a variety of operations must be conducted at a spectacle store or the like before spectacles having lenses set in a frame are supplied to an orderer. First, spectacle lenses to be used are determined at the spectacle store based on the prescription for the person who orders and the shape and size of a frame to be used, and an order for the lenses is placed with a lens manufacturer. The lenses, when delivered from the manufacturer, are edged and beveled with various machines at the spectacle store in accordance with the prescription, lens information and frame information. Thereafter, such lenses are fitted in the frame. In the following descriptions, a step of grinding lenses according to the frame shape is called "edging," and a step of forming a bevel on an edged lens is called "beveling."
The series of operations described above requires knowledge of spectacle lens optics, knowledge of ophthalmo-physiology, and a comprehensive technique of expertise-based framing and fitting for the adjustment of spectacles.
Presently, lenses to be used are determined by a skilled person, and not by an apparatus, taking the beveling step into consideration. Namely, a technique has not yet been developed for making calculations to predict shape of a beveled lens, and a disadvantage often arises in that a bevel cannot be formed at an optimal position because of an improper lens shape (external shape of the lens, shapes of the front and rear surfaces of the lens, lens thickness, etc.).
For example, the bevel curve of the spectacle lens may become moderate (less steep) compared with the curve of the frame (rim), depending on the bevel position selected, and in this case the frame is deformed so as to be matched with the bevel curve. However, deforming the frame can result in an increase of the frame size beyond the values calculated when the bevel position was selected, and thus in deficiency of the outer diameter or edge thickness of the lens.
When using a frame that may not be deformed, the bevel of the spectacle lens must be matched with the three-dimensional shape of the frame. Depending on the lens thickness and the frame shape, however, the bevel curve may extend out from the edge surface of the lens, making the bevel formation impossible.
Even though the lenses can be fitted in the frame, the outward appearance of the finished spectacles may be poor due to improper bevel position or improper lens shape, making the user feel dissatisfied with the spectacles. For example, the user may be discontented with the spectacles because the edge of the lens is too thick, or because the bulge of the front surface of the lens from the rim is too conspicuous. To avoid such awkward situations, a system is demanded by which the shape of finished lenses can be predicted for confirmation before actual lens processing, and which permits change of lenses to one made of a material having, e.g., a higher refractive index, or to one having a more moderate front curve, after the confirmation.
When formulating a spectacle lens supply system which can previously provide information as to whether a lens process including beveling is possible or not, so that lenses to be used can be determined or an optimum bevel can be set based on the information, the following preconditions are required. Namely, transmission of frame shape data from the orderer side to the processor side via a communication line must be as accurate as possible, and then reproduction of the frame shape at the processor side must be as accurate as possible; bevel process/design must be carried out in advance at the processor side so that beveled lenses can be properly fitted in the frame; a desired part of the predicted shape of finished lenses can be easily and closely examined at the order side; and so forth.